MSD Activator Window Switch - Experiences?

[Howieau]

Hey guys Im looking at getting an MSD Activator Window Switch for my ST185 GT4 to use in controlling the TVIS (2nd set of intake runners closed at low rpm to promote torque, then open around 4500rpm to allow more flow/power). Heres a pic and caption;

RPM Activated Switches will perform a variety of functions including turning on a bulb or solenoid or triggering secondary intake runners. The 8950 switch activates a circuit when the engine rpm reaches the value of the rpm module (sold separately below). The 8956 window switch uses two rpm modules, one to activate a circuit, and the second to deactivate the circuit. This is a great feature to deactivate nitrous before the engine's rev limit is reached.

The idea of using an MSD AWS and home-made rpm module is described on the following website;
http://www.corral.net/tech/powerplant/arm/

The idea is to do 2 dyno runs, one with the TVIS connected and one without and the RPM at which the torque curve intersects is the RPM you choose for the 2nd set of intake runners to open.

Has anybody tried this or something similar? Any experiences with the MSD activator switch or effectiveness of the home-made module?

Thanks in advance.
Has anybody tried a similar thing?

[mrshin]

Are you using the factory ECU? Then use the TVIS output. Are you using an aftermarket ECU? Then use one of the aux outputs.

[Howieau]

Ah good idea. Ill have to look into whether mine can run TVIS as you suggest but Im sure it does.

There is a way to hook up TVIS so that as soon as you hit boost it opens (run vacuum line from TVIS actuator to intake manifold). Would that give me an optimum torque curve?

Forgive me if this gets confusing, but heres an example of what im referring to. With the MSD switch, or my EMS, I can do the two dyno runs, one with TVIS open and one with it shut, then make the intersecting point of the two torque lines my TVIS opening point. If I hook it up just so as it hits boost it opens, would that give me a smooth torque line? Like, will a 4 cylinder turbo engine running 1 psi of boost give more torque than it can at any rpm in vacuum?

Im just not sure if as soon as boost kicks in, and the tvis opens, the torque will dip because the turbo isnt making as much torque as it was with the tvis shut in vacuum, if that makes sense.

[BeRad]

Maybe im completely wrong, but i would think toyota would have done extensive testing as to when the 2dn set of butterflies open, and that being at around 4300rpm?, depending on the mods youve done from standard i would imagine it would still be close to optimum?

[assassin10000]

You may end up needing to do 5 or 6 dyno runs (if not more) to figure out the optimum setup for the opening point of the TVIS.

You could find out that there is an optimum RPM point to open the TVIS, regardless of boost.

You may find out there is 2 good points to open tvis, one of each based on RPM & Boost (throttle load?).

Just thinking about the variables is going to be fun

I'd say probably minimum of 3 runs to get the basic idea, then choose a mid point where they intersect:
1 tvis closed, full throttle, boost
1 tvis open, full throttle, boost
1 tvis closed until it hits boost

Who knows, maybe the intersecting point will be the rpm where it reaches full boost (very likely IMO, as that's where the power comes on )

Andrew

[Howieau]

Yeh I think that might have to be the way, cheers